Keepers at Edinburgh Zoo believe she was successfully inseminated but lost the foetus at late term.

Tian Tian (Sweetie) has been keeping her carers at Edinburgh Zoo guessing over her possible pregnancy since she was artificially inseminated in April.

In August, experts noted signs she could be pregnant and it was hoped a panda cub would be born by September.

But a statement released this morning said: “All of her hormonal and behavioural signs now indicate that she had conceived and carried a foetus until late term, but then lost it.”

Chris West, chief executive of the Royal Zoological Society of Scotland (RZSS), which runs the zoo, said: “We are all saddened by this turn of events after so many weeks of waiting.

“Timings are difficult to pinpoint at this moment, but we had a meeting this morning where Tian Tian’s behaviour and hormone results were reviewed and have come to the conclusion that it is very likely she has lost the pregnancy.

“Up until now, Tian Tian has consistently shown signs of pregnancy. However, the veterinary team has noticed a significant decline in the amount of colostrum being produced and over the last few days she has returned to the normal eating and behavioural patterns of a non-pregnant panda.”